1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to techniques for HARQ recombining.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A wireless communication network may include a number of base stations that can support communication for a number of user equipments (UEs), also referred to as mobile devices or mobile entities. A UE may communicate with a base station via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station. As used herein, a “base station” means an eNode B (eNB), a Node B, a Home Node B, or similar network component of a wireless communications system.
The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) represents a major advance in cellular technology as an evolution of Global System for Mobile communications (GSM) and Universal Mobile Telecommunications System (UMTS). The LTE physical layer (PHY) provides a highly efficient way to convey both data and control information between base stations, such as an evolved Node Bs (eNBs), and mobile devices, such as UEs.
In an LTE network, one or more base stations may broadcast a public warning message to mobile devices to notify the respective users of a natural disaster or other emergency. For example, one or more base stations may broadcast an earthquake and tsunami warning system (ETWS) message to warn the users of an earthquake or tsunami. The warning message may be divided into a plurality of message segments, in which a base station broadcasts each message segment within a scheduled transmission window to mobile devices within the base station's coverage area.
To ensure that even a mobile device experiencing poor channel conditions can successfully decode a message segment, the base station may transmit the message segment multiple times within the respective transmission window. The mobile device may recombine the multiple transmissions of the message segment (e.g., using HARQ recombining) to decode the message segment. The mobile device may then combine the decoded message segment with other decoded message segments to recover the entire warning message, and display the warning message to the respective user.